WO2008090284A2

WO2008090284A2 - Method for correcting the geometry of a traced curve

Info

Publication number: WO2008090284A2
Application number: PCT/FR2007/002082
Authority: WO
Inventors: Romain Tesseraud
Original assignee: Essilor International (Compagnie Generale D'optique)
Priority date: 2006-12-18
Filing date: 2007-12-14
Publication date: 2008-07-31
Also published as: FR2910136A1; WO2008090284A3; US20100094589A1; EP2092268B1; FR2910136B1; EP2092268A2; US8205345B2

Abstract

The invention relates to a method for correcting the geometry of a traced curve. The inventive correction method comprises the following steps: a step for searching one or more abnormality areas (S1, S2) in the traced curve (19) and, if one more abnormalities are detected, for correcting the geometry of each abnormality area in the traced curve.

Description

"Method of correcting the geometry of a palpated curve approaching a longitudinal strand of a spectacle frame bezel and method of acquiring the geometry of an outline of such a bezel"

TECHNICAL FIELD TO WHICH THE INVENTION REFERS

The present invention relates generally to the field of eyewear and more specifically to the acquisition of the geometry of the outline of the bezel of a circle of a rimmed eyeglass frame. It relates to a method for correcting the geometry of a palpated curve approaching a longitudinal strand of a bezel of a circle of an eyeglass frame, as well as a method of acquiring the geometry of a contour. a bezel of a circle of a spectacle frame, comprising a feeler of the bezel by sliding or rolling of a feeler which is driven in the longitudinal direction of the bezel and which is biased transversely towards the bottom of the bezel, the deduction of the geometry of a palpated curve approaching a longitudinal strand of the bezel, and the correction of this palpated curve geometry.

The invention finds a particularly advantageous application in the reading of highly arched spectacle frames. TECHNOLOGICAL BACKGROUND

The technical part of the optician's profession is to mount a pair of ophthalmic lenses on a frame selected by a wearer. This assembly is broken down into three main operations:

the acquisition of the geometry of the outline of the bezel of each of the two circles of the eyeglass frame chosen by the future wearer, that is to say the geometry of the grooves which run through the inside of each circle of the frame ,

the centering of each lens which consists in determining the position that each lens will occupy on the frame so as to be properly centered facing the pupil of the wearer's eye so that it properly exerts the optical function for which it was designed,

the trimming of each lens which consists in machining or cutting its contour to the desired shape, taking into account the geometry of the outline of the bezel and the defined centering parameters, with, at the end of the machining, the beveling which consists of realizing on the edge of the lens an interlocking rib intended to hold the lens in the bezel that includes the circle of the frame.

In the context of the present invention, it is mainly concerned with the first operation of acquiring the geometry of the bezel contours of the circles of the chosen eyeglass frame. In practice, it is first of all, for the optician, to feel the bottom of the grooves of each of the two circles of the selected eyeglass frame in order to precisely determine the coordinates of a plurality of points characterizing the geometry of the eyeglass. a longitudinal strand of the bezel of each circle (in practice confused with the bottom ridge of the bezel). The knowledge of the geometry of this strand allows the optician to deduce the approximate geometry that must present the contour of the lens to be machined in order to be inserted into the corresponding circle of the spectacle frame.

The bezel generally having a dihedral section, the objective of this operation is in particular to follow exactly the bottom of the bezel that includes the circle to read, so as to memorize a precise digital image of the geometry of the contour of the bezel.

In the case of strongly "curved" and "poured" frames, that is to say strongly arched and twisted, a simple probing of the bezel does not give satisfactory results. The Applicant has indeed noticed that, despite the care taken in probing bezel frames such glasses, there are often difficulties in nesting lenses in these frames.

OBJECT OF THE INVENTION

In order to overcome the above-mentioned disadvantage of the state of the art, the present invention proposes a method of more precise acquisition of the geometry of the contours of the bevels of the circles of eyeglass frames.

More particularly, according to the invention there is provided a method for correcting the geometry of a palpated curve approaching a longitudinal strand of a bezel of a circle of a spectacle frame, comprising: a search for one or more possible anomalous zones of the palpated curve, and

if one or more anomaly zones are found, a correction of the geometry of each anomalous zone of the palpated curve.

The term "longitudinal strand of the bezel" a strand that belongs to one or the other side of the bezel and which is parallel or confused with the bottom ridge of the bezel. In other words, in each cross section of the bezel, each longitudinal strand has a tangent parallel to the tangent to the bottom edge of the bezel.

The Applicant has noticed that, in the case of strongly arched frames, a simple support of the probe on the bezel, in the middle plane of the circles of the eyeglass frame, does not allow the probe to accurately follow the bottom of the bezel. Indeed, when the "pouring" (or twisting) of the mount is very important and that one of the sides of the bezel is very inclined, it happens that the probe slides on this flank away from the bottom of the bezel without the optician can not realize. Therefore, when probing the bezel, one acquires not the exact geometry of a longitudinal strand of the bezel (confused with the bottom edge of the bezel), but rather the geometry of a curve approaching this longitudinal strand.

The invention proposes to identify these zones and to correct the shape of the curve read in these zones alone.

According to a first embodiment of the invention, said possible anomalous areas of the palpated curve are searched as areas in which the first or second derivative of a first function of at least one of the three coordinates of the curve palpated with respect to a second function of at least one other of the three coordinates of the palpated curve exceeds, in absolute value, a threshold value which is relative to the mount considered or which is absolute.

In order to detect the zones in which the probe has moved away from the bottom of the bezel, it is judiciously used that this reading error of the bezel results in a greater acceleration or a greater speed of the feeler than would normally be possible. if the probe remained in contact with the bottom of the bezel.

Indeed, when the probe deviates from the bottom of the bezel by sliding along one of the sides of the bezel, the acceleration of the probe oscillates abnormally and takes important values. Thus, an area of the bezel can be considered as an anomaly zone when the oscillations of the probe acceleration become very important in this zone.

The invention proposes then to determine, thanks to the geometry of the curve palpated along the bezel, the acceleration or the speed presented by the probe during the probing of the bezel, to deduce the position of the zones in which the probe has moved away from the bottom of the bezel, and to acquire the geometry of a curve better approaching the longitudinal strand of the bezel by correcting, in the zones of anomaly, the geometry of the initially palpated curve.

Advantageously, the search for possible areas of anomaly of the palpated curve includes the search for any angular sectors, identified around an inner axis and generally transverse to the palpated curve, in which the first or second derivative of a radial coordinate and or axial axis of the curve palpated with respect to another angular coordinate of the palpated curve is greater, in absolute value, than said threshold value. According to a second embodiment of the invention, the search for said possible anomalous zones of the palpated curve comprises the following steps:

- cutting the palpated curve into several cutting portions, - calculating an interpolating curve portion between the ends of each cutting portion of the palpated curve,

- Search, among the cutting portions of the palpated curve, any abnormal cutting portions deviating from the corresponding portion of the interpolation curve beyond a given threshold value, - Determination of said anomaly zones in function of any abnormal cutting portions found.

Thus, if the distance or the surface between the interpolation curve and the palpated curve exceeds in a zone a threshold value, this overrun means that the bezel has not been correctly palpated in this zone. It is then necessary to determine more precisely the shape of the curve palpated in this zone.

Advantageously, the cutting portions of the palpated curve partially overlap.

The threshold value can be determined in several ways.

It can be predetermined and common to several spectacle frames.

From a sampling of eyeglass frames representative of all existing eyeglass frames, an average threshold value is calculated which is suitable for a set of frames, that is to say which, for each frame, allows determine if the probe has moved away from the bottom of the bezel. The threshold value can be calculated according to the variations, over all or part of the palpated curve, of the first or second derivative of a first function of at least one of the three coordinates of the palpated curve with respect to a second function. at least one of the three coordinates of the palpated curve. The threshold value may be equal to a function of the standard deviation of the variation, over all or part of the palpated curve, of the first or second derivative of a first function of at least one of the three coordinates of the curve. palpated with respect to a second function of another at least one of the three coordinates of the palpated curve. The threshold value can be derived in part from at least one degree of camber of the spectacle frame calculated from the geometry of the palpated curve. Thus, when the eyeglass frame is identified as being slightly arched, and the risk that the probe has moved away from the bottom of the bezel is small, the threshold value can be increased so as to reduce the number of anomalous zones, which amounts to reducing the calculation time of the real geometry of the outline of the bezel. The probability of defining an area of the bezel as a zone of anomaly (that is to say imperfectly) read when it had actually been read correctly is also reduced. On the other hand, when the spectacle frame is identified as being very arched, and the risk that the probe has moved away from the bottom of the bezel is important, the threshold value can be reduced so as to ensure that all the zones having been misread are detected. The degree of camber of the frame can be calculated from the geometry of the curve palpated along the bezel. It can also be determined visually by the optician who then takes care of entering this data into the bezel contour reading device used. According to an advantageous characteristic of the invention, the search for possible zones of anomaly is carried out in the only temporal part of the circle of the eyeglass frame. Since the frames are generally only poured into the temporal portions of the circles of the frame, the feeler is likely to deviate from the bottom of the bezel only in these zones of the circles of the frame. Therefore, the search for anomaly areas is performed only in these only temporal parts of the circles of the frame, which allows to reduce the calculation time of the actual geometry of the outline of the bezel without affecting the accuracy calculations.

The correction of the geometry of each anomalous zone of the palpated curve can be performed:

by again feeling each abnormality zone of the outline of the bezel, the probe being controlled during this new probing according to second transverse and / or longitudinal positions of positions and / or forces depending on the anomaly zones found; or - by replacing the geometry of each anomalous zone of the palpated curve with a geometry reconstructed by calculation according to criteria of continuity of derivation order greater than or equal to 1 with the zones of the palpated curve adjacent to said zone d 'anomaly ; or

by palpating a plurality of points of the anomalous area of the bezel and substituting the geometry of the palpated curve in each anomaly zone with a geometry reconstructed by interpolation of said probed points.

The subject of the invention is also a process for acquiring the geometry of a contour of a bezel of a circle of an eyeglass frame, comprising a feeler of the bezel by sliding or rolling of a feeler which is driven in the longitudinal direction of the bezel and which is biased transversely towards the bottom of the bezel, the deduction of the geometry of a palpated curve approaching a longitudinal strand of the bezel, and the correction of this curve geometry palpated according to the method defined above.

Advantageously, the probing of the bezel being carried out by controlling the probe according to first transverse and / or longitudinal positions of positions and / or of forces, the correction of the geometry of each anomalous zone of the palpated curve is carried out by palpating at again each anomalous area of the bezel contour, the probe being controlled during the new probe according to second transverse and / or longitudinal positions of positions and / or different forces of said first instructions.

Advantageously then, there is provided an additional step of verification that the spectacle frame has remained motionless during the probing of the bezel. It happens that under the effect of the forces generated by the probe on the circle of the eyeglass frame, the mount moves when probing the bezel. This movement of the mount may distort the reading of the geometry of the outline of the bezel, and therefore distort the result of the search for abnormal areas of the bezel. It is therefore necessary to ensure the immobility of the frame. Check, after probing the bezel, that the starting point and end of the probe are confused, for example to ensure that the mount has not moved.

To make sure more surely, it is also possible to feel the bezel by driving the probe to realize more than one complete revolution, so as to read twice the same area of the bezel. Verifying that the positions of this zone at the beginning and at the end of the probing coincide to ensure that the spectacle frame has not moved.

If the eyeglass frame has not remained stationary, the entire outline of the bezel from which the geometry of the palpated curve is drawn is again probed.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The following description with reference to the accompanying drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be achieved.

In the accompanying drawings:

FIG. 1 is an overall perspective view of an apparatus for bevel contour geometry reading of a spectacle frame;

FIG. 2 is a perspective view of a portion of a bezel of the spectacle frame of FIG. 1;

FIG. 3 is a plan view of a palpated curve approaching the shape of the outline of the bezel of the spectacle frame of FIG. 1 superimposed with a graph representing in polar coordinates the variation of the radial acceleration of the probe of FIG. reading apparatus of Figure 1;

FIG. 4 is a graph showing the variation of the radial acceleration of the probe as a function of the angular position of this probe; FIG. 5 is a graph representing a binary function of the angular position of the probe, which is equal to 1 in the only zones of the bezel where the radial acceleration of the probe exceeds a threshold value;

FIG. 6 is a graph showing another binary function of the angular position of the probe, which is equal to 1 in the anomalous zones of the bezel; and

FIG. 7 is a plan view of the palpated curve of FIG. 3 after correction.

For the implementation of the method according to the invention, it is necessary to have a device for reading the geometry of the contours of the bezels of eyeglass frame circles. This reading device is a means well known to those skilled in the art and does not make the object of the invention described. For example, it is possible to use a reading device as described in patent EP 0 750 172 or marketed by Essilor International under the trademark Kappa or under the trademark Kappa CT. Figure 1 is a general view of this reading device 1, as it is presented to its user. This apparatus comprises an upper cover 2 covering the entire apparatus except for a central upper portion.

The reading apparatus 1 is intended to record the geometry of the inner contours of the bezels 11 of a spectacle frame 10 chosen by a wearer. The eyeglass frame 10 is here of circled type. It comprises two circles 14, namely a right circle and a left circle intended to be respectively positioned opposite the right eye and the left eye of the wearer when the latter carries said mount. It further comprises a bridge 17 linking the two circles 14 and two branches 18 each connected to one of the two circles 14. Each of the circles of the spectacle frame 10 is adapted to receive an ophthalmic lens provided on its edge with a bevel.

As shown in FIG. 2, the two circles 14 each have a inner groove, commonly called bezel 11, wherein the bevel of the corresponding lens is adapted to fit. Each bezel 11 has a section here dihedral (V), with a bottom edge 12 bordered by two sides 13. It could alternatively have a section of slightly different shape, for example U.

We will call here "longitudinal strand of the bezel" any strand that belongs to one or the other of the sides of the bezel and which is parallel or confused with the bottom edge 12 of the bezel 11. In particular, we will consider a first longitudinal strand confused with the bottom edge 12 of the bezel 11. The eyeglass frame 10 is here arched so that the bevels 11 are poured, that is to say twisted. Therefore, each cross section of the bezel 11 has a proper inclination. This inclination is generally minimal at the nasal areas of the circles of the mount (near the bridge 17) and maximum at the temporal zones of the circles of the mount (near the hooked areas of the branches 18 on the circles 14 of Frame).

The reading apparatus 1 shown in FIG. 1 comprises a set of two jaws 3, at least one of the jaws 3 is movable with respect to the other so that the jaws 3 can be moved closer together or apart from one of the jaws 3. another to form a clamping device of the mount. Each of the jaws 3 is further provided with two grippers each formed of two movable studs 4 to be adapted to clamp the spectacle frame 10 between them in order to immobilize it.

In the space left visible by the upper central opening of the cover 2, a frame 5 is visible. A plate (not visible) can move in translation on the frame 5 along a transfer axis D. On this plate is rotatably mounted a turntable 6. This turntable 6 is adapted to take two positions on the transfer axis D, a first position in which the center of the turntable 6 is disposed between the two pairs of studs 4 fixing the right circle of the eyeglass frame 10, and a second position in which the center of the turntable 6 is arranged between the two pairs of studs 4 fixing the left circle of the spectacle frame 10.

The turntable 6 has an axis of rotation B defined as the axis normal to the front face of the turntable 6 and passing through its center. It is adapted to pivot relative to the plate. The turntable 6 furthermore comprises an oblong slot 7 in the form of an arc of a circle through which a feeler 8 having a support rod 8A projects and at its free end a finger probing 8 B intended to follow by sliding or possibly rolling the longitudinal strand of each bezel 11 of the eyeglass frame 10.

The reading apparatus 1 comprises actuating means (not shown) adapted, on the one hand, to slide the support rod 8A along the light 7 in order to move it away from or towards the center of the turntable 6, and, on the other hand, to position the feeler finger 8B of the feeler 8 at a greater or lesser altitude relative to the plane of the front face of the turntable 6.

In summary, the probe 8 is provided with three degrees of freedom, including a first degree of freedom TETA consisting of the ability of the probe 8 to pivot about the axis of rotation B by rotating the turntable 6 relative to the plate, a second degree of freedom Z constituted by the ability of the probe 8 to translate axially along an axis parallel to the axis of rotation B of the turntable 6, and a third degree of freedom R constituted by the ability of the feeler 8 to move radially relative to the axis of rotation B thanks to its freedom of movement along the arc formed by the light 7.

Each point read by the end of the feeler finger 8B of the probe 8 is located in a corresponding coordinate system R, TETA, Z.

The reading apparatus 1 also comprises means for acquiring the position R, TETA, Z of the end of the feeler finger 8B of the probe 8. It also comprises means for controlling the actuating means of the probe 8. apparatus, for controlling the position of the end of the feeler finger 8B of the probe 8.

All of these acquisition and control means are integrated in an electronic and / or computer device 100 allowing, on the one hand, to actuate the actuating means of the apparatus, and, on the other hand, recovering and recording the data transmitted to it by sensors integrated in the reading device 1.

For the implementation of the method according to the invention, with reference to FIG. 1, prior to starting the probing of the bezel 11 of each circle 14 of the eyeglass frame 10, the eyeglass frame 10 is first fixed in the eyeglass frame 10. reading device 1. For this, the frame is inserted between the pads 4 of the jaws 3 so that each of the circles of the frame is ready to be palpated along a path starting by the insertion of the probe 8 between two corresponding pads 4 at the lower part of the frame, then following the bezel 11 of the frame, to cover the entire circumference of the circle 14 of the spectacle frame 10.

We will study here more particularly the acquisition of the geometry of the outline of the bezel of the left circle of the eyeglass frame.

As shown in FIG. 3, the acquisition means define as zero the angular position TETA of the probe 8 when its end is disposed on the side of the nasal zone of the circle 14 of the frame, at a right angle with respect to its position. insertion between the two studs 4.

Once the eyeglass frame 10 is fixed, the control means control the rotation of the turntable 6 so that the end of the feeler 8 moves longitudinally along the bottom edge 12 of the bezel 11.

Preservation of the contact of the feeler finger 8B with the bezel 11 is provided by the actuating means. The latter exert on the probe 8 a radial return force directed towards the bezel 11, which allows the feeler finger 8B to remain in contact with the bezel 11.

Thus, the probe 8 is controlled in the TETA angular position around the axis of rotation B and is guided according to its radial coordinate R and according to its altitude Z through the V-shaped bezel.

The sensors of the reading apparatus 1 are, during rotation of the turntable 6, the spatial coordinates of a plurality of points of the bezel, for example 360 points, for storing a precise digital image of the outline of the bezel 11. this operation is in particular that the bezel remains throughout the duration of probing the bezel 11 as much as possible in contact with the bottom edge 12 of the bezel 11.

However, as shown in Figure 2, when the frame is strongly curved and some areas of the bezel 11 are well versed, it happens that the probe slides along one of the sides 13 of the bezel and deviates from the bottom ridge 12 of the bezel.

The electronic and / or computer device 100 thus deduces from this probing, not the exact geometry of the first longitudinal strand (coincides with the bottom edge of the bezel), but rather the geometry of a palpated curve 19 approaching the geometry of the first longitudinal strand of the bezel.

The objective of the invention is therefore to redefine the geometry of the palpated curve 19 in the zones where the feeler 8 has moved away from the bottom of the bezel 11 to define a new geometry of the palpated curve closer to that of the first strand. longitudinal. Following the probing operation of the bezel 11 of the left circle 14 of the spectacle frame 10, the electronic and / or computer device 100 proceeds to a verification step that the spectacle frame 10 has remained still for the duration of the probing of the bezel 11. To do this, it compares the spatial coordinates of the starting and ending points of the probe 8.

If the mount has remained stationary during the probing of the bezel 11, these points are merged. On the other hand, if the mount has moved, these points have different spatial coordinates. In this case, the electronic and / or computer device conducts a second probing of the entire contour of the bezel 11.

Alternatively, it is also possible to feel the bezel by controlling the feeler so that it performs more than one complete revolution, so as to read twice the same area of the bezel. The verification that the positions of this zone at the beginning and at the end of the probing coincide makes it possible to ascertain even more surely that the spectacle frame has not moved.

At the end of this verification step, if the spectacle frame has not moved, the electronic and / or computer device 100 proceeds to a step of searching for the possible anomalous zone (s) of the contour of the bezel 11. For this, the device comprises calculation means which:

calculate the first or second derivative of a first function of at least one of the three coordinates (R, THETA, Z) of the palpated curve 19 with respect to a second function of at least another of the three coordinates R, THETA, Z of the palpated curve 19;

search for the anomaly zones as zones of the palpated curve in which this first or second derivative exceeds, in absolute value, a threshold value VS.

In the present case, the calculation means determine, as a function of the angular position TETA of the points of the palpated curve 19, the second derivative of the radial coordinates R of the points of the palpated curve 19 with respect to their angular positions TETA. The result of this calculation is shown in FIGS. 3 and 4. The variation of this second derivative corresponds to the variation of the radial acceleration d ² (R) / d (TETA) ² of the probe 8 during the probing of the bezel 11.

FIG. 3 shows in particular that the zones in which the radial acceleration of the probe 8 oscillates strongly correspond to the anomalous zones S1, S2 imperfectly read from the bezel 11. In other words, the oscillations of the radial acceleration of probe 8 indicate a misreading of the bezel by the probe.

The calculation means therefore define an area of the bezel as "anomalous area" an area in which the radial acceleration of the probe 8 exceeds, in absolute value, a threshold value VS. It is therefore an imperfectly read area.

This threshold value VS is here predetermined, that is to say constant regardless of the spectacle frame installed in the reading device 1. It may for example be equal to 400 microns / rad ² .

As a variant, the threshold value may be, not absolute, but relative to the eyeglass frame chosen by the wearer and installed in the reading device.

1. According to this variant, the threshold value is calculated as a function of the variations, over the entire contour of the bezel 11, of the radial acceleration of the probe 8. This threshold value may for example be formed by an average value of the variation the radial acceleration of the probe, or by the standard deviation of this variation over the entire contour of the bezel 11.

According to another embodiment of the invention, the threshold value can be chosen according to the degree of camber of the spectacle frame. Indeed, the more the eyeglass frame is arched, the greater the probability that areas of the bezel 11 have been poorly read by the probe 8 is large. The threshold value must therefore be chosen lower for heavily curved frames. In this variant, the electronic and / or computer device 100 determines the difference between the maximum altitude Z and the minimum altitude Z of the palpated curve 19; this difference is proportional to the degree of camber of the eyeglass frame. Depending on whether this difference is respectively less than or greater than a limit value (for example

15.8 millimeters), the threshold value is chosen more or less.

Whatever the threshold value VS chosen, in order to determine the angular sectors S1, S2 in which the anomaly zones of the left circle 14 of the eyeglass frame 10 are located, the electronic and / or computer device processes the variations the radial acceleration of the probe 8.

For this, it defines a binary function f, represented in FIG. 5, which is a function of the angular position TETA of the probe 8. This binary function f is defined as being equal to 1 when the radial acceleration of the probe exceeds, as a value absolute, the threshold value VS chosen, and if not equal to 0.

In order to reduce the computation time of the binary function f, this function can be directly defined as zero in the angular sectors of the circles where the bezel is poorly poured. Therefore, it can be defined as zero when the TETA angular position of the probe is between 90 and 270 degrees (for the right circle, this range is between -90 and 90 degrees). As shown in FIG. 4, the radial acceleration of the probe exhibits oscillations, so that in the same zone of strong oscillations corresponding to a single anomalous area S1, S2 of the bezel, the radial acceleration of the probe passes successively to above and below the threshold value VS. The binary function f thus presents, for the same zone of strong oscillations, a succession of slots.

In order to obtain a single slot per zone of strong oscillations, the electronic and / or computer device 100 determines a filtered function g, represented in FIG. 6, which is a function of the angular position TETA of the probe 8. This filtered function g is defined as being equal to 1 not only in the angular sectors where the binary function f is equal to 1, but also in the angular sectors situated between two slots of the function f, provided that these two slots are close to one of the other (angularly separated by less than 3.5 degrees for example). Thus, the anomalous areas of the bezel, whose angular sectors are separated by an angular interval less than a predefined minimum interval, are concatenated to define together a global zone of anomaly. It happens that several portions of the outline of the bezel are imperfectly read by the probe. In each of these portions of the outline of the bezel, the derivative of the trajectory of the probe can oscillate strongly around zero. Each passage of the derivative above the threshold value defines a small zone of the bezel as a zone of anomaly imperfectly read. These oscillations thus generate a plurality of small zones of anomaly which correspond in fact to the same portion of the abnormal or imperfectly read bezel. According to the invention, these small areas of anomaly are assembled so as to define only one and the same global zone of anomaly so as not to distort the calculations for correcting the geometry of the palpated curve.

As an alternative to the search for anomalous areas by exceeding a first or second derivative threshold, it is possible for the calculating means to search for said possible anomalous areas S1, S2 of the palpated curve 19 by the implementation next steps.

The electronic and / or computer device 100 cuts the palpated curve into several cutting portions. For a finer analysis of the curve, it will be provided that the cutting portions of the palpated curve 19 are partially superimposed.

The electronic and / or computer device 100 then determines a portion of the interpolation curve between the ends of each portion of cutting of the palpated curve 19. For this purpose, the electronic and / or computer device 100 calculates, for each chopping portion, the coefficients of an interpolation polynomial Q (TETA) _1, for example of order 3, constructed according to continuity criteria with the zones of the palpated curve 19 adjacent to the corresponding cutting portion. Of course, one could also use a higher order interpolation polynomial. These continuity criteria are as follows. Let P1 and P2 be the two end points which delimit one of the cutting portion of the palpated curve, whose spatial coordinates are respectively R1, TETA1, Z1 and R2, TETA2, Z2. Then, the coefficients of the interpolation polynomial Q (TETA) are calculated so that at the point P1, this polynomial function is equal to R1 and the derivative of this function is equal to the derivative of order 1 at the point P1 of the radial coordinate R of the palpated curve 19 with respect to its TETA angular coordinate, namely:

Q (TETAI) = R1 and dQ (TETA) / dTETA _TE τA = τETAi = dR / dTETA _{R = R1} In addition, the coefficients of the interpolation polynomial Q (TETA) are calculated so that at point P2, this function polynomial is equal to R2 and the derivative of this function is equal to the derivative of order 1 at the point P2 of the radial coordinate R of the palpated curve 19 with respect to its angular coordinate TETA, that is: Q (TETA2) = R2 and dQ (TETA) / dTETA _TE τA = τETA2 = dR / dTETA _{R = R2}

An interpolation polynomial is thus defined as an interpolation curve portion associated with each cutting portion of the palped curve of the bezel.

The calculating means then seek, among the cutting portions of the palpated curve 19, any abnormal cutting portions deviating from the corresponding interpolation curve portion beyond a given threshold, for example by using the maximum deviation or standard deviation between the interpolated radius and the measured radius. For example, it may be considered that a cutting portion is abnormal when the maximum deviation on this portion is greater than a threshold value of between 0.5 mm and 1 mm depending on the desired sensitivity, or when the standard deviation is greater than a threshold value of between 0.1 millimeter and 0.2 millimeter depending on the desired sensitivity.

The calculation means finally determine the anomalous areas S1, S2 as a function of any abnormal cutting portions found. In any event, at this stage, the anomalous areas S1, S2 of the bezel 11 are therefore known from the electronic and / or computer device 100; they are indeed in the angular sectors in which the filtered function g is 1. In the example illustrated in FIGS. 2 to 6, the outline of the bezel 11 has two anomalous zones S1, S2 both located on the side of the temporal portion of the left circle 14 of the spectacle frame 10.

The electronic and / or computer device then proceeds to a step of correcting the geometry of the palpated curve 19 in these anomalous zones S1, S2.

To do this, the device replaces the parts of the geometry of the palpated curve 19 located in the anomalous areas S1, S2, parts reconstructed by calculation. The geometries of these reconstructed parts are here defined mathematically by polynomial functions.

For this purpose, the electronic and / or computer device 100 calculates, for each reconstructed part, the coefficients of an interpolation polynomial Q (TETA), for example of order 3, built according to criteria of continuity with the zones of the palpated curve 19 adjacent to the corresponding anomaly zone. This interpolation polynomial is in this case the same as that used previously to define the portion of the interpolation curve associated with each cutting portion, in the second implementation variant of the calculation of the determination of the anomaly zones. Of course, it would also be possible to use here a different interpolation polynomial, in particular a higher order polynomial.

With reference to FIG. 3, these continuity criteria are as follows. Let P1 and P2 be the two end points which delimit one of the anomalous zones S1 of the bezel 11, whose spatial coordinates are respectively R1, TETA1, Z1 and R2, TETA2, Z2. Then, the coefficients of the interpolation polynomial Q (TETA) are calculated so that at the point P1, this polynomial function is equal to R1 and the derivative of this function is equal to the derivative of order 1 at the point P1 of the radial coordinate R of the palpated curve 19 with respect to its TETA angular coordinate, namely:

An interpolation polynomial is thus defined by zone of abnormality of the bezel. These polynomials define reconstructed curves for replace the incompletely read anomaly areas of the palpated curve 19. This assembly of curves defines a new corrected curve 20 which is shown in FIG. 7, which is continuous and which does not show any points of inflection. Its geometry is then very close to that of the first longitudinal strand.

Alternatively, the reconstruction of anomalous areas of the bezel can be performed differently, by means of a probing of these areas.

Thus, the correction of the geometry of the palpated curve 19 can be performed by palpating a second time each anomalous area S1, S2 of the outline of the bezel 11, and replacing the poorly read zones of the palpated curve 19 by curves of which the shapes are defined from this second probing of the bezel 11. For this purpose, the control means of the reading device 1 control the probe 8 in these anomalous areas S1, S2, so as to feel the bezel at a very low speed. This very low speed makes it possible to ensure that the probe 8 remains in contact with the bottom of the bezel 11 and does not deviate from its trajectory by sliding on one of the sides 13 of the bezel 11.

The correction of the geometry of the palpated curve 19 can otherwise be carried out by palpating a plurality of points of the anomalous zones S1, S2 of the bezel 11 and by replacing the geometry of the palpated curve 19 in these anomalous zones with a geometry reconstructed by interpolation of said probed points. The interpolation polynomial then used has an order that is a function of the number of points probed on each anomaly area. This variant makes it possible to ensure that the reconstructed geometry is very close to the real geometry of the first longitudinal strand, even if the zone of anomaly extends over a large angular sector.

According to another embodiment of the invention, the search for anomalous areas of the bezel can be performed, not from the radial acceleration of the probe but rather from its axial acceleration along the axis of rotation B The threshold value used is then different, for example 100 microns / rad ² ; the method for implementing the invention remains however identical.

The search for imperfectly read zones of the bezel can also be carried out not only from the radial acceleration of the probe 8, but also from its axial acceleration. In this case, when either of these accelerations exceeds the threshold value associated with it, the palpated zone is defined as an anomaly zone.

Alternatively, the search for anomalous areas of the bezel can be performed, not from the radial acceleration of the probe but rather from its radial velocity and / or axial. The implementation of this variant is identical to that described above, only the threshold values used change. For example, a radial probe threshold of 5 mm / rad or an axial speed threshold of 1 mm / rad can be set.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind.

Claims

1. A method of correcting the geometry of a palpated curve (19) approaching a longitudinal strand (12) of a bezel (11) of a circle (14) of a spectacle frame (10), characterized in that that it comprises:

a search for one or more anomalous zones (S1, S2) of the palpated curve (19), and

if one or more anomalous areas (S1, S2) are found, a correction of the geometry of each anomalous area (S1, S2) of the palpated curve (19).

The method according to claim 1, wherein said possible areas of anomaly (S1, S2) of the palpated curve (19) are searched as areas in which the first or second derivative of a first function of the one at least three coordinates (R, THETA, Z) of the palpated curve (19) with respect to a second function of at least one other of the three coordinates (R, THETA, Z) of the palpated curve (19) exceeds, in absolute value, a threshold value (VS) relative to the frame considered or absolute.

3. Method according to the preceding claim, wherein the search for possible areas of anomaly (S1, S2) of the palpated curve (19) includes the search for any angular sectors (S1, S2), marked around an axis ( B) inner and generally transverse to the palpated curve (19), wherein the first or second derivative of a radial (R) and / or axial (Z) coordinate of the palpated curve (19) relative to another angular coordinate (TETA) of the palpated curve (19) is greater, in absolute value, than said threshold value (VS).

4. The method of claim 1, wherein the search for said possible areas of anomaly (S1, S2) of the palpated curve (19) comprises the following steps:

- cutting the palpated curve (19) into several cutting portions, - calculating an interpolating curve portion between the ends of each cutting portion of the palpated curve (19),

searching, among the cutting portions of the palpated curve (19), of any abnormal cutting portions deviating from the corresponding interpolation curve portion beyond a given threshold value; anomalies (S1, S2) as a function of any abnormal cutting portions found.

5. Method according to the preceding claim, wherein the portions cutting of the palpated curve (19) overlap partially.

6. Method according to one of claims 2 to 5, wherein said threshold value (VS) is predetermined and is common to several spectacle frames (10).

7. Method according to one of claims 2 and 3, wherein said threshold value (VS) is calculated as a function of the variations, over all or part of the palpated curve (19), of the first or second derivative of a first function of at least one of the three coordinates (R, THETA, Z) of the palpated curve (19) with respect to a second function of at least one of the three coordinates (R, THETA, Z) of the palpated curve (19).

8. Method according to the preceding claim, wherein the threshold value (VS) is equal to a function of the standard deviation of the variation, over all or part of the palpated curve (19), of the first or second derivative of a first function of at least one of the three coordinates (R, THETA, Z) of the palpated curve (19) with respect to a second function of at least one other of the three coordinates (R, THETA, Z) of the palpated curve (19).

9. Method according to one of claims 2 to 5, wherein said threshold value (VS) is derived in part at least one degree of camber of the spectacle frame (10) calculated from the geometry of the curve palpated (19).

10. Method according to one of claims 2 to 5, wherein the search for possible areas of anomaly (S1, S2) is performed in the only temporal portion of the circle (17) of the spectacle frame (10).

11. Method according to one of the preceding claims, wherein the correction of the geometry of each anomalous area (S1, S2) of the palpated curve (19) is performed by palpating again each anomalous area (S1, S2) of the contour of the bezel (11), the probe (8) being controlled during this new probing according to second transverse and / or longitudinal positions of positions and / or forces depending on the anomalous areas (S1, S2) found .

12. Method according to one of claims 1 to 10, wherein the correction of the geometry of each anomalous area (S1, S2) of the palpated curve (19) is performed by substituting the geometry of each zone of anomaly (S1, S2) of the palpated curve (19), a geometry reconstructed by calculation according to derivation order continuity criteria greater than or equal to 1 with the zones of the palpated curve (19) adjacent to said zone of anomaly (S1, S2).

13. Method according to one of claims 1 to 10, wherein the correction of the geometry of each anomalous area (S1, S2) of the palpated curve (19) is achieved by palpating a plurality of points of the zone d 'anomaly (S1, S2) of the bezel (11) and substituting the geometry of the palpated curve (19) in each anomalous region (S1, S2), a geometry reconstructed by interpolation of said probed points.

14. A method of acquiring the geometry of a contour of a bezel (11) of a circle (14) of an eyeglass frame (10), comprising a probing of the bezel (11) by sliding or rolling a feeler (8) which is driven in the longitudinal direction of the bezel (11) and which is biased transversely towards the bottom of the bezel (11), the deduction of the geometry of a palpated curve (19) approaching a longitudinal strand ( 12) of the bezel (11), and the correction of this curve geometry palpated according to the method of one of the preceding claims.

15. Method according to the preceding claim, wherein the probing of the bezel (11) being performed by controlling the probe (8) according to first transverse and / or longitudinal positions and / or efforts, the correction of the geometry of each anomalous zone (S1, S2) of the palpated curve (19) is produced by again feeling each abnormality zone (S1, S2) of the outline of the bezel (11), the probe (8) being controlled during this again probing according to second transverse and / or longitudinal positions of positions and / or different forces of said first instructions.

16. Method according to one of claims 14 and 15, comprising an additional step of verifying that the spectacle frame (10) has remained stationary during the probing of the bezel (11).

17. Method according to the preceding claim, comprising, if the spectacle frame (10) has not remained stationary, a new probing of the entire contour of the bezel (11) which is deduced the geometry of the curve probed (19). ).